Additive manufacturing, also known as 3D printing, has in recent years been used for a wide variety of applications, thereamong to manufacture tools for metal cutting machining. It basically involves processing a powdery starting material layer by layer with a laser beam, such that the individual powder particles bond to one another. Individual powder particles may for example melt with or sinter with one another layer by layer to form a solid body. This manufacturing method makes it possible to easily form complex geometrical structures in one piece, which have not been possible or realistic to achieve with previous conventional manufacturing methods.
Two different methods are commonly used in additive manufacturing: Direct Metal Deposition (DMD) and Selective Laser Melting (SLM). In DMD, a laser beam is used to form a melt pool on a metallic substrate. Metal powder is fed into the laser beam such that a fusion bonded deposit is formed on the substrate. The required geometry is built up layer by layer.
SLM is a process in which a 3D CAD model of the required geometry is first sliced into a number of finite layers. For each layer, a laser scan path is calculated, defining on one hand the boundary contour and on the other hand some form of fill sequence. Each layer is thereafter sequentially recreated by depositing powder layers, one on top of the other, and locally melting the powder layers by scanning a laser beam. The process enables complex geometries to be generatively produced in a single operation.
US 2015/0298222 discloses a tool for metal cutting machining which has been manufactured using additive manufacturing with a tool steel powder as a starting material. The tool has a tool body of which a portion is formed with a solid outer jacket encasing a core structure. The core structure comprises a three-dimensional open non-solid core structure formed in one piece with the outer jacket. In other words, the tool body is partly hollow. With such a tool body, the weight of the tool can be reduced in comparison with a solid tool manufactured using conventional manufacturing processes. However, reducing the amount of material in the tool body may also impact the strength of the tool as well as its stiffness, and thereby render it less suitable for demanding applications.